ENDOCRINE REGULATIONS, Vol. 32, 187 – 191, 1998
187
ACCURACY AND SIGNIFICANCE OF FINE-NEEDLE ASPIRATION
CYTOLOGY AND FROZEN SECTION IN THYROID SURGERY
F. TANERI, A. POYRAZ1, E. TEKIN, E. ERSOY, A. DURSUN1
Gazi University Medical Faculty Departments of General Surgery and Pathology1, Besevler, Ankara, Turkey
Objective. In the retrospective study to review the records of patients who had undergone thyroid surgery between 1986-1995 and to determine the need of frozen section (FS) following FNA
biopsy.
Methods. The records of 2083 patients who had thyroid surgery in Gazi University Medical
Faculty Department of General Surgery between 1986-1995 were retrospectively reviewed to determine and compare the accuracy and significance of fine-needle aspiration (FNA) cytology and
intraoperative frozen section (FS).
Results. In 61 patients, both FNA and FS diagnosis were available for the comparison with the
final pathologic diagnosis. In 196 patients, FNA diagnosis was available for the comparison with
the final pathological diagnosis by permanent section and in 377 patients FS diagnosis was available for the comparison with the final pathological diagnosis. The sensitivity value for detection of
malignancy by means of FNA was 57.1 % compared to 82.2 % by means of FS, and FS diagnosis
was more specific (99 %) than FNA diagnosis (90.9 %). FNA diagnosis of benign conditions was
correct in 141 of 150 (94 %) patients. FS diagnosis of benign conditions was correct in 313 of 321
(97.5 %) patients. Nine patients had the FNA findings that were positive for malignancy and FS
confirmed this diagnosis in 8 patients.
Conclusions. FNA is an important diagnostic tool for eliminating benign nodules, but it is not
perfect. FS is very important for determining the surgical procedure, and because of direct observation of suspicious nodule, it is even more accurate. Using these tools together is more reliable,
since the number of false positive and false negative values is lower than if only the individuals
methods are used.
Key words: Fine-Needle Aspiration - Frozen Section - Thyroid - Surgery
It has been estimated that palpable thyroid nodules occurr in about 5 % of population and, in addition, autopsy series have revealed that as much as 80
% of the population has thyroid nodules (TUNBRIDGE
1977; VANDER 1968). With the widespread use of
ultrasonography, large numbers of thyroid nodules
are detected and the selection of patients for surgery
appears a problem for surgeons. In the absence of
pressure symptoms, the main indication for surgery
is the risk of malignant disease. While the incidence
of malignancy is around 20 % for single nodules,
this number declines to 10 % for multiple nodules
(MESSARIS 1974; ROJESKI 1985). In such countries like
Turkey, where goiter is endemic, the incidence of
malignant disease is around 5 % (ÇIFTER 1987). Preoperative assessment of thyroid nodules is generally
performed by ultrasonography, radionuclide scanning
and fine-needle aspiration (FNA). FNA biopsy is
the most preferred test and has improved the selection of patients for thyroid surgery (ASHCRAFT 1981;
ROJESKI 1985; HAWKINS 1987; LENGUIST 1987; KÖHLER
1988). However, it is not clear whether the extend of
surgery can be determined with FNA biopsy alone
or whether frozen section examination should be
done to confirm the diagnosis. In a number of hospitals in developing countries, frozen section exam-
188
FINE-NEEDLE ASPIRATION THYROID CYTOLOGY
ination is not available and, when available, it may
be time consuming and expensive. Furthermore, in
developing countries FNA and frozen section examinations are carried out by pathologists who are not
specialized in thyroid pathology and therefore the
sensitivity and specificity may be different from these
in specialized centers.
In this retrospective study, the records of patients
who had undergone thyroid surgery between 19861995 were reviewed to determine the need of frozen
section (FS) following FNA biopsy.
Table 1
Distribution of malignant thyroid tumors
Papillary carcinoma
Occult papillary carcinoma
Follicular carcinoma
Anaplastic carcinoma
Hurtle Cell carcinoma
Medullar carcinoma
Immunoblastic lymphoma
Follicular and hurtle Cell carcinoma
Malignant fibrous histiocytoma
TOTAL
78
19
15
8
2
1
1
62%
15%
12%
6%
1.6%
0.7%
0.7%
1
1
0.7%
0.7%
126
Materials and Methods
The records of 2083 patients who had thyroid surgery between 1986-1995 were retrospectively reviewed. A total of 634 patients had either FNA biopsy, FS examinations or both. For remaining patients
FNA or FS was either not indicated or was not available. Thus, 634 patients (52 males and 582 females,
median age 47 years, range 21-67) were the objective of this study.
All 634 patients had their final pathological examination by permanent section of the resected specimen. Out of them, a total of 196 patients had preoperative FNA, 377 patients had FS examinations and
61 had both FNA and FS diagnosis. The findings
obtained by FNA and FS were compared with the
final pathological diagnosis and from these data the
accuracy, sensitivity, specifity, positive and negative
predictive values, false positivity and false negativity rates were calculated.
Results
A total of 126 thyroid malignancies were detected
among the total 2083 patients who had thyroidectomies (6 %) (Tab. 1). On the other hand, 53 patients
had malignant disease among the 634 patients who
had FNA, FS, or both (8.4 %).
In 196 patients FNA diagnosis was reported as
malignant in 26 patients (13.3 %), benign in 150 (76.5
%), and undetermined in 20 (10.2 %). When compared with the final permanent section there were 9
false negative and 14 false positive FNA diagnosis.
Among 20 FNA undetermined patients permanent
section diagnosis were benign in 19 and malignant
in only one which was papillary carcinoma. On the
other hand, final permanent section pathological diagnosis revealed malignant disease in 6 % and benign disease in 94 % of 2083 patients. FNA diagnosis of benign conditions was correct in 141 of 150
patients (94 %). Among the nine false negative FNA
patients, permanent section revealed seven papillary
carcinomas, one hurtle cell carcinoma, and one follicular carcinoma. Of the 26 patients with FNA diagnosis of malignant disease, 14 had benign and 12
had malignant nodules. In 20 patients with undetermined FNA diagnosis, one had papillary carcinoma
and 19 had benign pathologies. When undetermined
FNA diagnosis were excluded, FNA sensitivity was
57 %, accuracy 87 %, positive predictive value 46
%, negative predictive value 94 %, false positivity
rate 8 %, and false negativity rate was 5 % (Tab. 1).
FS examination was performed in 377 patients.
FS diagnosis was reported to be malignant in 40 patients (11 %), benign in 321 (85 %), and diagnosis
was undetermined in 16 patients (4 %). Final pathological examination showed benign disease in 329
(87.3 %) and malignant disease in 48(12.7 %). FS
diagnosis of benign conditions was correct in 313 of
321 patients (98 %). Among the eight false negative
FS diagnosis, permanent section showed five papillary carcinomas and three follicular carcinomas. Of
the 40 patients with malignant disease in FS, 37 (92.5
%) had malignant and 3(7.5 %) had benign pathologies on permanent section. FS sensitivity was 82 %,
accuracy 97 %, positive predictive value 93 %, negative predictive value 98 %, false positivity rate 0.8
%, and false negativity rate was 2 % (Tab. 2).
Sixty one patients had both preoperative FNA and
FS examination. The details of pathological findings
189
FINE-NEEDLE ASPIRATION THYROID CYTOLOGY
Table 2
Frozen section and permanent section results
Table 4
Thyroid FNA and FS results
PERMANENT SECTION
Malignant
Benign
Total
FROZEN
SECTION
Frozen (-)
Permanent (-):
45
Malignant
Benign
Undetermined
37
8
3
3
313
13
40
321
16
FNA (+)
Frozen (+)
Permanent (+):
8
FNA (+)
Frozen (-)
Permanent (+):
2
Total
48
329
377
FNA (+)
Frozen (-)
Permanent (-):
2
FNA (+)
Frozen (+)
Permanent (-):
1
FNA (-)
Frozen (-)
Permanent (+):
1
FNA (-)
Frozen (+)
Permanent (+):
2
Table 3
Thyroid FNA and permanent section results
PERMANENT SECTION
Malignant
Benign
Total
FNA
FNA (-)
Malignant
Benign
Inadequate
12
9
1
14
141
19
26
150
20
Total
22
174
196
are given in Tab. 3. Sensitivity was 89 %, accuracy
96 %, positive predictive value 89 %, negative predictive value 98 %, false positivity rate 2 %, and false
negativity rate was 2 %.
Discussion
The large number of thyroid nodules in the countries where goiter is endemic, complicates the selection of patients for surgery. Before the advent of FNA
biopsy, the decision was based on physical examination, radionuclide scanning and ultrasonography.
However, this schedule forced the surgeons to operate a number of patients, while relatively small number of malignant nodules were detected. In other
words, several patients underwent the thyroidoctomy which was not absolutely necessary. Thus, ÇIFTER
(1987) reported the group of patients in which the
incidence of malignant nodules was significantly
higher in those who had preoperative histopathologic diagnosis with FNA and/or FS. It can be argued
that these tests are preferred for suspicious nodules
and this can be, at least partly, true for FS examination. But FNA is now routinely done in all cases of
palpable thyroid nodules and a selection bias is prevented. Mainly from such reason FNA appeared to
be great help for surgeons.
FNA of thyroid nodules has been shown to be safe,
accurate, and superior to clinical assessment in cases
Total:
61
(-) are benign and (+) malignant
of malignant thyroid disease (COLACCHIO 1980; GRIFIES 1985; HOLLEMAN 1985; MANDREKER 1995; BURCH
1996). Several studies have revealed that, the incidence
of false positive findings ranged from less than 1 % to
9 % and false negatives from 0 % to 4 % for FNA
(LOWHAGEN 1979; COLACCHIO 1980; BOEY 1984; GRIFIES 1985; TAKASHIMA 1994). If such accurate FNA data
are available, continued use of FS procedures can be
justified only if they would provide more accurate information or if they would alter the choice of surgical
approach. Our results are in accordance with the previous findings, since FNA sensitivity was 57 %, accuracy was 87 %, positive predictive value was 46 %,
negative predictive value was 94 %, false positive rate
was 8 % and false negative rate was 5 %. In previous
studies, the evaluation of FS diagnosis shows that the
incidence of false positive is 2 % and false negative
value is 9 % (KELLER 1987; LAYFIELD 1991; GIBB 1995).
Our results are in accordance with the previous findings as; FS sensitivity was 82 %, accuracy was 97 %,
positive predictive value was 93 %, negative predictive value was 98 %, false positive rate was 0.8 % and
false negative rate was 2 %. When FNA and FS results are considered together; sensitivity was 89 %,
accuracy was 96 %, positive predictive value was 89
%, negative predictive value was 98 %, false positive
rate was 2 % and false negative rate was 2 % (BOUVET
1992; SCHMID 1989; VOJVODICH 1994). The efficiency
of FNA is better when it is guided by ultrasonography
and also core needle biopsy showed better results than
FNA (TAKASHIMA 1994; LIU 1995).
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FINE-NEEDLE ASPIRATION THYROID CYTOLOGY
FNA alone seems to be reliable to diagnose benign nodules, but positive predictive value and sensitivity were found to be low in this study. FS alone
or FS following FNA has improved the results considerably. Both FS and FNA biopsies were not carried out by pathologists specialized in thyroid diseases as in most developing countries. As this study
was carried out in a university hospital, it should be
born in mind that lower accuracy rates should be
expected in other hospitals. In the absence of specialized cytologists, FS examination has yielded a
better result with pathologists.
It is thus concluded that, FNA biopsy should be
used routinely for thyroid nodules as a preoperative screening test. This improves the selection of
patients for surgery and may reduce the number
of unnecessary thyroidectomies. However, FS examination should be used when ever possible, as
this significantly improves the diagnosis of malignant thyroid disease. This obviously, is very
important for the surgeon in deciding the extent
of surgery.
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Corresponding author: Ercüment Tekin M.D.
Turan Günes Blv. 41.
Sok. Aktürk Sitesi 2.
Kýsým A blok / 6 Oran
Ankara, TURKEY
Accepted: June 15, 1998